Resistance material



.metal and glass powders.

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2,415,03 RESISTANCE MATERIAL Archibald 0. Quinn, Detroit, Mich, assignor to I Bendix Aviation Corporation, Detroit, Mich, a corporation of Delaware No Drawing. Application October 13, 19M,

Serial No. 558,611

Claims. (Cl. 201-76) break switches, the material being characterized in that the possibility of arcing of the switch is inhibited.

Another object of the invention is to provide a highly efficient electrical resistance element made of metal and glass powders intimately mixed.

It has been found that an electrical resistance element-proves eminently satisfactory for general use in electric circuits when the element is made of a material derived from a compound of In the preparation of the resistance material through the use of metal and glass powders, a critical percentage of metal is essential before the material becomes conductive. .In instances where either copper or nickel powder is used of a -325 mesh, 9, minimum of forty-two per cent (42%) of metal is found to be essential.

In practice, the maximum specific resistance thus far attained in the usage of copper and glass, and nickel and glass is- Copper and glass. .025 Nickel and glass '.125

Although these values have been obtained, they are by no means static. The percentage of metal used and the resultant specific resistance is controlled by the mesh size of both constituents, the thoroughness of mixing the constituents, and the manner of curing the material,

1 that is, the heat treatment of the compound.

, Ohm. cm. Copper -.0000017 and Nickel -.00000'l8 ample, a compound of However, it is to be clearly understood that the invention is not limited to the use of copper and nickel. As to the metallic element of the material, any other metal may be employed with excellent results.

Although the resistance obtained through the use of a mixture of copper and glass, and also a mixture of nickel and glass, is much higher than in instances where pure nickel or copper elements are used, in some instances it is necessary to obtain higher resistances than obtainable with either of the above compositions.

It. has been discovered that with the addition of silicon as athird element in the compound, the resistance values are enormously increased. This is clearly shown by actual tests; as, for ex- Per cent Copper 40 Silicon 10 Glass 50 has a resistance value of 1.17

Percent Nickel 35 sincbn 15 Glass 50 has a resistance of 3.10 ohm. cm. A material composed of silicon 25% and glass 75% has a resistance value of 1,000,000 ohm. cm. Thus, the value of silicon has a constituent of the compound becomes clearly evident.

Through the use of a compound of glass, silicon and metal, preferably copper or nickel, a resistance material may be varied through wide limits. The variation of resistance may be obtained in the following manner; 1. e., by keeping the percentage of glass constant and varying the percentage of silicon and nickel; by keeping the silicon constant and varying the percentage of nickel and glass; bykeeping the nickel constant and varying the percentage of silicon and glass; and .also by varying the particular mesh of the respective constituents of the compound.

It has been found that a highly satisfactory resistance bar may be had by compounding the following materials in the percentages given;

In preparing this compound the wax is dissolved v acmpso in carbon tetrachloride. The metal powders and glass powder are then mixed and added to the wax solution. This mixture is placed in,a ball mill and more carbon tetrachloride is added to form a thin slurry. The mixture is then thoroughly milled, drained ofi, and dried. When thoroughly dried, it is screened through a fine mesh screen.

temperature; for example, 1000 F. for fifteen minutes. Then, to attain the desired physical characteristics of the bar, it is re-sintered at a The material is loaded into a steel die and compressed to the contour of the piece "desired. In order to removev'olatile constituents from the pressed bar, it is then sintered at a low 4 the invention,, what I claim as new and desire to secure by Letters Patent is:

1. A resistance material comprising powdered glass 50%, powdered copper 40%, and powdered silicon 10%.

2.'A resistance material comprising a compound of glass powder 50%, nickel powder 35%, and silicon powder 15%.

3. A resistance material comprising the following constituents compounded in the proportions given: powdered glass 57.5 parts; powdered silicon 8.0 parts, and powdered nickel 34.5 parts.

4. A resistance bar comprising a compound of powdered glass 57.5 parts, powdered silicon 8.0 parts, powdered nickel 34.5 parts, and ,paraffln wax 7.5 parts, in solution, thoroughly mixed, dried, compacted, and sintered.

5. The method of producing a resistance bar comprising compounding glass powder 57.5 parts, silicon powder 8.0 parts, nickel powder 34.5 parts, and parafin wax 7.5 .parts, drying the mixture, compacting the mixture to form the bar. and sintering th bar.

. ARCHIBALD C. QUINN. 

